Alternating current (ac) voltage regulator and method of operating the same

ABSTRACT

An alternating-current (AC) voltage regulator including an input, an isolated power supply, a control circuit, an amplifier, and an output. The input is configured to receive an input voltage. The isolated power supply is configured to receive the input voltage and output a direct-current (DC) signal isolated from the input voltage. The control circuit is configured to receive a portion of the input voltage, adjust the portion of the input voltage, and output the adjusted voltage. The amplifier is configured to receive the isolated DC signal, the adjusted voltage, and a feedback loop, and output a differential signal. The output is configured to add the differential signal to the input voltage resulting in a regulated voltage, and output the regulated voltage.

RELATED APPLICATIONS

This application claims priority to U.S. patent application Ser. No.16/899,184, filed Jun. 11, 2020, which claims priority to U.S.Provisional Patent Application No. 62/862,926, filed Jun. 18, 2019, theentire contents of both of which are hereby incorporated by reference.

FIELD

Embodiments relate to alternating-current (AC) voltage regulators.

SUMMARY

AC voltage regulators may use magnetic, mechanical, variants offerro-resonance, servo-variac, tap changing, and/or electrical switchingto perform AC voltage regulation. Such systems operate by regulatingapproximately 100% of the power received with approximately 90%efficiency. For example, regulation of 500 watts using such systems mayrequire conversion of all 500 watts to regulate voltage. As a result,such systems and methods may not only be overly large, but alsoexpensive to manufacture and expensive to operate.

Thus one embodiment provides an alternating-current (AC) voltageregulator including an input, an isolated power supply, a controlcircuit, an amplifier, and an output. The input is configured to receivean input voltage. The isolated power supply is configured to receive theinput voltage and output a direct-current (DC) signal isolated from theinput voltage. The control circuit is configured to receive a portion ofthe input voltage, adjust the portion of the input voltage, and outputthe adjusted voltage. The amplifier is configured to receive theisolated DC signal, the adjusted voltage, and a feedback loop, andoutput a differential signal. The output is configured to add thedifferential signal to the input voltage resulting in a regulatedvoltage, and output the regulated voltage..

Another embodiment provides a method of regulating analternating-current (AC) voltage. The method includes receiving, via aninput, an input voltage, and outputting, via an isolated power supply, adirect-current (DC) signal isolated from the input voltage. The methodfurther includes receiving, via a control circuit, a portion of theinput voltage, adjusting, via the control circuit, the portion of theinput voltage, and outputting the adjusted voltage. The method furtherincludes receiving, via an amplifier, the isolated DC signal, receiving,via a the amplifier, the adjusted voltage, receiving a feedback loopfrom an amplifier output to a second input of the amplifier, andoutputting, via the amplifier, a differential signal. The method furtherincludes adding the differential signal to the input voltage resultingin a regulated voltage, and outputting, via the output, the regulatedvoltage.

Such embodiments may maximize efficiency and lower costs by providingproper regulation without the need to regulate entire line voltage. Inone embodiment of operation only 10% of the power may actually beconverted. Thus, for example, only 50 watts (of a total of 500 watts)may be converted to regulate the voltage, while the remaining 450 wattsis allowed to pass by on the line.

Furthermore, such embodiments do not need to regulate when regulation isunnecessary. Whereas systems that incorporate magnetic, mechanical,variants of ferro-resonance, servo-variac, tap changing, and/orelectrical switching to perform regulation often times must stillconvert 100% of the power received regardless if regulation is actuallynecessary.

As a result of only requiring to convert approximately 10% of the totalpower, and only regulating when necessary, the above describedembodiment may be approximately 1/50^(th) the size and weight of ACvoltage regulators using magnetic, mechanical, variants offerro-resonance, servo-variac, tap changing, and/or electrical switchingto perform regulation. Furthermore, the above described embodiment maybe approximately 1/10^(th) the cost of AC voltage regulators usingmagnetic, mechanical, variants of ferro-resonance, servo-variac, tapchanging, and/or electrical switching to perform regulation.Additionally, such efficiencies may lead to reduced costs of operationcompared to systems that incorporate magnetic, mechanical, variants offerro-resonance, servo-variac, tap changing, and/or electrical switchingto perform regulation.

Other aspects of the application will become apparent by considerationof the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an alternating current (AC) regulatoraccording to some embodiments.

FIG. 2 is a flowchart illustrating an operation of the AC regulator ofFIG. 1 according to some embodiments.

DETAILED DESCRIPTION

Before any embodiments of the application are explained in detail, it isto be understood that the application is not limited in its applicationto the details of construction and the arrangement of components setforth in the following description or illustrated in the followingdrawings. The application is capable of other embodiments and of beingpracticed or of being carried out in various ways.

FIG. 1 is a block diagram of a regulator 100 according to someembodiments. In some embodiments, the regulator 100 may be a voltageregulator, such as but not limited to, an alternating current (AC)series pass voltage regulator configured to regulate a voltage on a line102.

In operation, the regulator 100 may be configured to receive a portionof an input voltage from line 102 and add a differential voltage signalback onto line 102, resulting in a regulated voltage (for example, avoltage having a predetermined amplitude and frequency). In someembodiments, partial power regulation is used to achieve the regulatedvoltage by adding the differential voltage signal to the input voltage.

The regulator 100 may regulate line voltage by converting only a portionof the total power of the line voltage. For example, the regulator 100may only convert approximately 10% of the total power (e.g., 50 watts ofa total of 500 watts), while the remaining 90% of the total power (e.g.,450 watts) is allowed to pass by (for example, via line 102). As aresult, a regulator 100 having 70% efficiency (i.e., a 30% loss), is 70%efficient on only approximately 10% of the total power. Therefore, theregulator 100 may regulate the line voltage with a total efficiency of97% (i.e., a 3% total loss).

Furthermore, the regulator 100 may only regulate line voltage whenneeded. For example, when the input line voltage already has thepredetermined amplitude and frequency, the regulator outputs adifferential voltage signal having approximately zero volts. In such anembodiment, the regulator 100 is using idle or rest current and notconversion power. Such operation leads to even greater efficiencies.

In the illustrated embodiment, the regulator 100 includes an input 105,a control circuit 110, an amplifier 115, a pulse-width modulated (PWM)power supply 120, and an output 125. The input 105 is configured toreceive an input voltage from line 102. In some embodiments, the inputvoltage is within a range of approximately 95VAC to approximately135VAC. The input voltage may be split-phase AC or three-phase AC.

The control circuit 110 is configured to receive at least a portion ofthe input voltage, adjust the input voltage, and output the adjustedvoltage. In some embodiments, the control circuit 110 may receiveapproximately 10% of the power of the input voltage (for example, 50watts of a total of 500 watts), while the remaining 90% of the power(for example, 450 watts) passes by via line 102. In some embodiments,the control circuit 110 adjusts the amplitude and/or phase of theportion of the input voltage.

In some embodiments, the control circuit 110 includes a zero crossingdetector 130 and a filter 135. In such an embodiment, the portion of theinput voltage may be received by the zero crossing detector 130 from theinput 105. The zero crossing detector 130 may be configured to convertthe portion of the input voltage from a sine wave to a square wavehaving a regulated amplitude. In some embodiments, the zero crossingdetector 130 includes one or more opto-couplers. In other embodiments,the zero crossing detector 130 includes one or more transformers. Insome embodiments, the zero crossing detector 130 is rail-to-rail immuneto input voltage variations, harmonics, and noise.

The square wave having the regulated amplitude may then be received bythe filter 135. The filter 135 may receive the square wave having theregulated amplitude, adjust the phase of the received square wave, andoutput the adjust wave as a filtered sine wave having adjusted amplitudeand phase.

In some embodiments, the filter 135 is, or includes, a bandpass filterand/or an all-pass filter. In such an embodiment, the bandpass filtermay include a Chebyshev 4^(th) order filter followed by a 1^(st) orderButterworth filter. Such a bandpass filter may induce an unwanted phaseshift that may be removed by the all-pass filter.

In other embodiments, the control circuit 110 is a digital signalprocessor (DSP). In such an embodiment, the DSP is configured to receivethe portion of the input voltage and output a sine wave having adjustedamplitude and phase.

The amplifier 115 is configured to receive the adjusted voltage andoutput a differential voltage signal. In some embodiments, the amplifier115 is a class D audio amplifier. In other embodiments, the amplifier115 is a class T audio amplifier. In some embodiments, the amplifier 115has a bandwidth of approximately 20 kHz. In such an embodiment, theamplifier 115 may correct harmonics and distortions occurring up toapproximately 20 kHz, thereby functioning as an active voltage harmonicand/or hash filter.

The amplifier 115 may include a first input 140, a second input 145,power inputs 150, and an output 155. In the illustrated embodiments, thefirst input 140 is a non-inverting input and the second input 145 is aninverting input.

In one embodiment of operation, the amplifier 115 receives the adjustedvoltage at input 140 and outputs, via output 155, the differentialvoltage signal. In some embodiments, the amplifier 115 is an invertingamplifier, including for example, an inverting control loop 160. Theinverting control loop 160 may be a feedback loop electricallyconnecting the output 155 to the second input 145. In some embodiments,the control loop 160 may include a digital signal processor (DSP)configured to providing inverting feedback to the amplifier 115.

In the illustrated embodiment, the output 155 and the control loop 160are electrically isolated from each other via isolator 165. In someembodiments, the isolator 165 includes one or more opto-isolators. Inother embodiments, the isolator 165 is a transformer.

The pulse-width modulated (PWM) power supply 120 is configured toconvert the input voltage to a direct-current (DC) voltage. In someembodiments, the PWM power supply 120 is an isolated power supply. Insuch an embodiment, the PWM power supply 120 may be an isolated AC/DCswitched mode power supply.

The PWM power supply 120 may provide isolated DC voltage to the powerinputs 150 of the amplifier 115. Thus, the amplifier 115 may beelectrically isolated from the input voltage at both the power inputs150 and the second input 145 (via feedback loop 160).

In operation, the regulator 100 receives the input voltage (for example,a line voltage) at input 105. A portion (for example, approximately 10%of the total power) of the input voltage is received by the controlcircuit 110, while the remaining (for example, approximately 90% of thetotal power) of the input voltage passes by the regulator 100 via line102.

The control circuit 110 receives a portion of the input voltage, adjuststhe amplitude and phase of the voltage, and outputs the adjusted voltageto the amplifier 115. The amplifier 115, based on at least the adjustedvoltage received at input 140 and the isolated feedback loop received atinput 145, outputs a differential voltage signal. The amplifier 115 maybe powered via isolated DC voltage from the PWM power supply 120. Thedifferential voltage signal is then added to the by-passed input voltageresulting in a regulated voltage on line 102.

In some embodiments, the regulator 100 may further include protectioncircuitry. The protection circuitry may provide additional protection tothe regulator 100 including, but not limited to, protection fromshorting issues. In some embodiments, the protection circuitry mayinclude, but is not limited to, a mechanical relay, a solid-state relay,and/or a dual MOSFET.

FIG. 2 is a flowchart illustrating an operation 200 of the regulator 100according to some embodiments. It should be understood that the order ofthe steps disclosed in operation 200 could vary. Although illustrated asoccurring in serial order, in other embodiments, the steps disclosed maybe performed in parallel order. Furthermore, additional steps may beadded to the process and not all of the steps may be required

At block 205, an input voltage (for example an AC voltage) is receivedat input 105. A direct-current (DC) signal is output from the AC/DC PWMpower supply 120 (block 210). In some embodiments, the DC signal isisolated from the input voltage (for example, via the AC/DC PWM powersupply 120).

A portion of the input voltage is received by the control circuit 110(block 215). An amplitude and a phase of the portion of the inputvoltage is adjusted via the control circuit 110 (block 220). The controlcircuit 110 outputs the adjusted voltage (block 225).

The DC signal is received via power input 150 of the amplifier 115(block 230). The adjusted voltage is received via input 140 of theamplifier 115 (block 235). A feedback loop from amplifier output 155 isreceived by input 145 of the amplifier 115 (block 240). A differentialsignal is output via amplifier output 155 (block 245). The differentialsignal is added to the input voltage, resulting in a regulated voltage(block 250), and the regulated voltage is then output (for example, viaoutput 125) (block 255).

Embodiments provide, among other things, an alternating current (AC)voltage regulator. Various features and advantages of the applicationare set forth in the following claims.

What is claimed is:
 1. An alternating-current (AC) voltage regulatorcomprising: an input configured to receive an input voltage; an isolatedpower supply configured to receive the input voltage and output adirect-current (DC) signal isolated from the input voltage; a controlcircuit configured to receive a portion of the input voltage, adjust theportion of the input voltage, and output the adjusted voltage; anamplifier configured to receive the isolated DC signal, receive theadjusted voltage, receive a feedback loop, and output a differentialsignal; and an output configured to add the differential signal to theinput voltage resulting in a regulated voltage, and output the regulatedvoltage.
 2. The AC voltage regulator of claim 1, wherein an output ofthe amplifier is electrically isolated from an input of the amplifiervia an isolator.
 3. The AC voltage regulator of claim 2, wherein theisolator includes at least one selected from a group consisting of oneor more opto-isolators and a transformer.
 4. The AC voltage regulator ofclaim 1, wherein the isolated power supply is an AC/DC pulse-widthmodulated (PWM) power supply.
 5. The AC voltage regulator of claim 1,wherein the control circuit adjusts at least one selected from a groupconsisting of an amplitude of the portion of the input voltage and aphase of the portion of the input voltage.
 6. The AC voltage regulatorof claim 1, wherein the control circuit is a digital signal processor(DSP).
 7. The AC voltage regulator of claim 1, wherein the controlcircuit includes a zero crossing detector.
 8. The AC voltage regulatorof claim 7, wherein the zero crossing detector is configured to receivethe input voltage, detect a zero cross of the input voltage, and adjustthe input voltage based on the zero cross.
 9. The AC voltage regulatorof claim 7, wherein the zero crossing detector includes one or moreopto-isolators.
 10. The AC voltage regulator of claim 7, wherein thezero crossing detector includes one or more transformers.
 11. The ACvoltage regulator of claim 1, wherein the control circuit includes afilter.
 12. The AC voltage regulator of claim 11, wherein the filter isa bandpass filter.
 13. The AC voltage regulator of claim 11, wherein thefilter includes a digital signal processor (DSP).
 14. The AC voltageregulator of claim 1, wherein the amplifier is at least one selectedfrom a group consisting of a class D audio amplifier and a class T audioamplifier.
 15. The AC voltage regulator of claim 1, wherein the inputvoltage is at least one selected from a group consisting of asplit-phase voltage and a three-phase voltage.
 16. The AC voltageregulator of claim 1, wherein the regulated voltage has a frequency ofat least one selected from a group consisting of 50 Hz, 60 Hz, and 400Hz.
 17. The AC voltage regulator of claim 1, wherein the feedback loopincludes a digital signal processor (DSP).
 18. A method of regulating analternating-current (AC) voltage, the method comprising: receiving, viaan input, an input voltage; outputting, via an isolated power supply, adirect-current (DC) signal isolated from the input voltage; receiving,via a control circuit, a portion of the input voltage; adjusting, viathe control circuit, the portion of the input voltage; outputting theadjusted voltage; receiving, via an amplifier, the isolated DC signal;receiving, via a the amplifier, the adjusted voltage; receiving afeedback loop from an amplifier output to a second input of theamplifier; outputting, via the amplifier, a differential signal; andadding the differential signal to the input voltage resulting in aregulated voltage; and outputting, via the output, the regulatedvoltage.
 19. The method of claim 18, further comprising: receiving, viaa zero crossing detector, the input voltage, detecting, via the zerocrossing detector, a zero cross of the input voltage, and adjusting, viathe zero crossing detector, the input voltage based on the zero cross.20. The method of claim 18, wherein the control circuit includes atleast one selected from a group consisting of a zero crossing detectorand a digital signal processor (DSP).